On board a vehicle, many systems use navigation parameters (position, speed, data relating to the environment, etc.). These parameters must have sufficient accuracy and integrity in order to be made available to user or pilot systems.
By accuracy it is meant the difference with respect to the true (theoretical) value of a parameter that it is sought to measure. Accuracy can be more easily defined in terms of an absolute fault or percentage. By integrity it is meant the ability to provide correct parameter values with respect to reality, even in the event of a failure.
In this connection, a distinction is drawn between failures known as “simple” failures, i.e. failures occurring on a particular piece of equipment, and failures known as “generic” or “common-mode” failures, affecting all hardware or software of the same type or having a similar technology.
These common-mode failures can for example originate from equipment or program design faults, extreme environmental conditions (high temperatures, vibrations, etc.), or also faults linked to the installation, maintenance or degradation of a piece of equipment.
At present, the system and functional architectures are based on the following components and algorithms: sensors, making it possible to collect measurement data relating to navigation parameters of a vehicle; computers containing algorithms known as fusion algorithms, making it possible to process redundant measurement data sent by the sensors, these computers being accommodated both in certain sensors and in the systems using the parameter values thus collected; and links or networks, making it possible to link the sensors to the user systems containing the fusion algorithms.
The design of the aircraft of the future must meet two major challenges: on the one hand reducing the aircraft's environmental footprint and on the other hand the presence of more automation on board the aircraft in order to reduce the pilot's workload (for example: extension of the scope of the Autopilot).
In order to meet the first objective, reducing the weight of the device is essential. In this context, it can be useful to reduce the number of pieces of equipment on board, the number of cables, and to optimize communication between the different systems. In order to meet the second objective, it is necessary to extend the availability of the flight parameters compared with the state of the art.
In this context, a drawback of the state of the art lies in the fact that several fusion algorithms of the navigation parameters are contained in different systems which have to be supplied with the different navigation parameter measurements.
Given that the existing devices use several fusion algorithms contained in computers accommodated both in the sensors and the user systems, each algorithm has specific features (inputs, comparison thresholds, confirmation times, etc). Their performances are therefore necessarily heterogeneous.
Furthermore, when a modification is necessary in order to obtain a given parameter, it has to be duplicated in each of the sensors or user systems, leading to significant costs in terms of time and resources.
In addition, other objects, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.